It's undeniably more materially efficient to re-power serviceable vehicles but people get their the panties in knot over safety so I doubt the "reverse glider" approach will ever gain a big foothold in the light vehicle market. It would likely be targeted by legislation that makes it economically non-viable if that were to happen.

Considering that the venn diagram between "people who profess to care a lot about safety" and "people who profess to care a lot about the environment" has a pretty massive overlap I look forward to the inevitable dumpster fire as people are forced to reconcile that the tradeoffs exist.

Furthermore, a ton of ancillary stuff has improved so much over the last 20+yr that the cumulative difference is quite noticeable. Few people will drop "new Mitsubishi Mirage" money re-powering an '03 Civic.